Screw-feed stoker



.I. S. SKELLY.

SCREW FEED STOKER. APPLICATION FILED ov. '19, 1919.

1",405, 94s, Patented Feb. 7, 1922.

m F? mwalls 4 of air chambers.

SCREllV-FEEID S'LOIKER.

Application filed November 19, 1919.

To /27 whom it may concern:

Be it known that it. Jon): S. SKELLY, a citizen of the i nited b'tates,residing at ltionongahela. county of lVashington. State of Pennsylvania,have invented a certain new and useful improvement in Screw-FeedStoker's. of which the following is a full. clear, and exactdescription.

My invention relates to screw feed stokers and has for its object toprovide a new and improved screw .feed stoker. One feature consists inthe use of two feed screws in the same retort. acting together on thesame body of coal to move it through the retort. Another featureconsists in means for rotating such juxtaposed screws in oppositedirections, while another feature consists in the relative position ofthe threads of the two screws.

The invention may be employed in stokers of various kinds. .but forconvenience is shown embodied in a stoker built somewhat upon the linesof the stoker shown in patent to V. R. Wood, No. 818,010, granted AprilThe following is a description of an embodiment of my invention,reference being had to the accompanying drawing, in which,

Fig. 1 shows a transverse section of a stoker embodying my invention;

Fig. 2 shows a longitudinal section partly on the line 22 and partly onthe line 2*2 Fig. 1, with end portions of each screw broken away inorder to more clearly show the portions of the other screw;

Fig. 3 shows in end elevation two adjacentstokers and a single means foroperating the screw feeds therein; and

Fig. 4: shows a plan view of adjacent portions of juxtaposed screws usedin embodying my invention.

eferring more particularly to the drawing, 1, 2 are stationary andmovable tubular grate bars of a stoker grate having their upper endssupported by Walls 3 of a retort and their lower ends supported. by Thebars 2 are provided with lugs forming notches in which flanges 5 uponoscillating rocker bars 6 fit so that when the bars 6 are oscillated thegrate bars 2 are reciproca.ed.- 7 is an ordinary dumping ash grate. Therocker bars 6 are supported by walls 8, which with the walls 4 form thesecondary air chainbers l0 and with the walls 3 form primary PatentedFeb.

Serial air passages 9 for air supplied to the inner ends of the bars 1and 2. The bars 1 and 2 are tubular, as shown in dotted lines, havinginlet ports at their upper ends connecting with the incoming airchambers 9 and outlet ports at their lower ends discharging into the airchambers 10. 11 is a hopper for holding the supply of fuel which at itslower end discharges into a passage in line with the retort and directlyupon the forward ends of the screws. In the retort are two paralleljuxtaposed feed screws 12 and 13 mounted on suitably journaled shafts.the screw 12 having a right-hand screw and the screw 13 having aleft-hand screw. These screws are so disposed t rit'their faces along ahorizontal plane passing through their diameters are always opposite toone another, as shown in Fig. 4, and correspond ing points in theirfaces uniformly approach each other during the travel of the pointsbelow the plane of the axes of .the screws and uniformly move away fromeach other during the travel of the points above the plane of the axesof the screws. The screws taper toward their inner ends so that thecapacity of the'screws uniformly decreases toward their inner ends andthe axes of the screws converge toward their inner ends so that thescrews are uniformly in close proximity throughout their extent. Thescrews are also in close proximity with the bottom of the retort and theretort is shaped to conform with the peripheries of the lower portion ofthe screws as shown in Fig. 1. lVith this construction it will beapparent that the screws will uniformly co-operate to feed the fuel fromthe time it leaves the hopper until it passes from the retort, and thescrews will act directly and uniformly on all the fuel at the bottom ofthe retort as well as the rest of the/fuel without the assistance ofboosters or similar devices. Attached to the sides of the retort areoverhanging deflectors 14 and 15, which assist in holding the screws inplace and also aid in the distribution of the fuel passing through theretort and upward to the grate bars. The screws 13 of two adjacentstokers (Fig. 3) are driven clockwise by gears 16 through screws 17mounted on a common shaft 18. Connected to the shafts of the screws 13are geared pinions 19 which mesh with gear pinions 20 mounted upon theshafts of the screws 12 so that when the gears 13 are rotated clockwisethe gears 12 are rotated countercloclnvise.

The screws 12 and 13 taper toward their inner ends so that the capacityof the screws as they extend to the back end of the retort decreases,with the result that they tend to cause the fuel to rise at all pointsalong the length of the retort.

With this construction, when fuel is placed in the hopper 11 it comes incontact with the ends of the juxtaposed screws adjacent to the mouththereof and is pro: pelled by their joint action into and along theretort, filling the same so that it flows over upon the upper ends ofthe grate bars down which it moves slowly. on account of thelongitudinal movements of the movable bars. The inner sides of the twoscrews, being the sides which move upward, assist in producing theupward flow of the fuel as well as in producing the longitudinalmovement thereof. The curved lower surfaces of the deflectors 14 and 15assist in holding the screws in place, while their curved upper surfacesassist in directing the flow of fuel upwardly toward the top of theretort and the upper ends of the grate bars. In Fig.

3 I have shown a plurality of stokers operated from a single screw shaft18 and it is obvious that the number operated from that same shaft canbe varied as desired, and that the speed of the feed can be varied byvarying thespeed of the shaft 18.

As is common in this general, type of stoker, air is fed into thetubular passages of the bars through the inlet ports at their upper endsand dise'harged through the outlet ports' at their lower ends into theair chambers 10 beneath the grate from which it passesupwardthrough thegrate to the superimposed fuel. The feeding mechanism is simple andefiicient' and is particularly adapted for supplying fuel to stokergrates of the movable tubular bar type.

As will be evident to those skilled in the art, my invention permits ofvarious modifications without departing from the spirit thereof orthescope of the appended claims.

What I claim is:

1. In a stoker furnace, a retort having at its bottom two juxtaposedrotating feed screws, a hopper discharging directlyupon 3. A stokerfurnace having in combination a retort, two co-operating feed screws atthe bottom of the retort tapering toward their inner ends and arrangedwith their axes converging toward their inner ends to position thescrews with their peripheries a uniform distance apart throughout theirextent, and means for rotating the screws in opposite directions.

4. A stoker furnace having in combination a retort, a pair of screwscapable of rotating in opposite directions extending longitudinally .ofthe retort and arranged in close proximity to each other and to thebottom of the retort to enable them to cooperate to feed the fueldirectly from the bottom of the retort, and means for thus rotating thescrews. I

5. A stoker furnace having in combina tion a retort, a pair of feedscrews capable of rotating in opposite directions extendinglongitudinally of the retort and constructed and arranged with theirfaces along a horizontal plane passing through their diametersoppositeto one another so that the movements of corresponding points in theiredges uniformly approach each other during the travel of the pointsbelow the plane of the axes of the screws and uniformly move away fromeach other during the travel of thepoints above the axes of the screws,and means for thus rotating the screws.

6. A stoker furnace having in combination a single chamber retort, twofeed screws therein extending the length thereof and juxtaposed so'as tobe closely adjacent to one another, gears connecting the screws so as tocause them to turn in opposite direc tions, a hopper dischargingdirectly over the outer ends of the screws, and means for rotating saidgears.

JOHN S. SKELLY.

